IT Series Woofers and Compression Drivers Enclosure and Crossover Applications The HC Design IT Series low frequency woofers and high frequency drivers are very high performance transducers designed for sound reinforcement and public address applications where excellent intelligibility and clarity are required. HC Design offers complete enclosure design plans as well as passive crossover designs optimized for use with the IT Series components. Additionally, there are two complete passive crossovers that are available for use with all IT Series products. IT SERIES LOUDSPEAKER COMPONENTS The IT Series consists of three low frequency components: the IT 18, IT 15 and IT 12. Each component is designed for specific applications and is optimized for superior amplitude and time domain performance. There are also three high frequency drivers: the IT 77N, IT77F, and IT44. PASSIVE CROSSOVERS There are two high performance passive crossovers available for use with all IT Series components. The IT 12PC was designed for use with the IT 12 woofer and the IT 15PC was designed to be used with the IT 15 woofer. Each crossover has an on-board jumper that allows the specific woofer to be used with the IT 77 N (neodymium), the IT 77 F (ferrite) or the IT 44 compression driver. The image below shows a rendering of the passive crossover printed circuit board and the jumper. The jumper is connected to the pin labeled IT 77N, IT 77F, or IT 4, based on which specific IT series driver is being used. The jumper must be moved to the correct position based on the specific driver being used. The jumper configuration is identical for both the IT 12PC and the IT 15PC.
Figure 1: The IT crossover showing the jumper wire. Figure 2: Close up view of the IT crossover shown jumper labels. HC Designs offers the passive crossover schematic free of charge but does not offer individual components. The IT 12PC and IT 15PC passive crossover assemblies may be purchased from HC Design.
H SERIES HORNS HC Design offers two very high performance constant directivity horn designs. Both horns are fully rotatable. H64 The H64 is a 60 degree by 40 degree medium to long throw horn that is ideal for applications that require long throw and a controlled coverage pattern. The H64 is an excellent choice in applications where large crowds are present or in long and narrow venues. The H64 has a square mouth profile and is fully rotatable so that the desired acoustic radiation angles may be rotated in either the horizontal or the vertical plane. The H64 is a constant directivity design. The H64 horn may be used with the IT15-PC crossover in the following configurations: 152B enclosure: IT 77N driver - jumper position 1 IT 77F driver - jumper position 2 IT 44 driver - jumper position 3 and 3825 adaptor 152S enclosure: IT 77N driver - jumper position 1 IT 77F driver - jumper position 2 IT 44 driver - jumper position 3 and 3825 adaptor The H64 horn may also be used with the IT12-PC crossover in the following configurations: 122S enclosure: IT 77N driver - jumper to position 1 IT 77F driver - jumper to position 2 IT 44 driver - jumper to position 3 and 3825 adaptor H94 The H94 is a 90 degree by 40 degree short throw horn that is optimized for use in wide venues and is also ideal for monitoring applications. The H94 has a square mouth geometry and is fully rotatable to allow the desired acoustic radiation angles to be rotated in either the horizontal or vertical plane. The H94 is a constant directivity design. The H94 horn may be used with the 115PC crossover in the following configuration: 152B enclosure: IT 77F driver - jumper to position 2 and Driver polarity REVERSED
The H94 horn may also be used with the 112PC crossover in the following configurations: 122S enclosure: IT 77F driver jumper to position 2 and Driver polarity REVERSED IT 44 driver jumper to position 2 and Driver polarity REVERSED 122M enclosure: IT 77F driver jumper to position 2 and Driver polarity REVERSED IT 44 driver jumper to position 2 and Driver polarity REVERSED ENCLOSURE DESIGNS HC Design also offers enclosure plans for use with all IT Series components and horns. There are two 15 inch two way designs and two 12 inch two way designs. 152B The 152B is a large enclosure volume trapezoidal design that offers extremely extended and high acoustic output bass response. The 152B features an IT 15 in an optimally vented enclosure and incorporates either a fully rotatable 60 degree by 40 degree constant directivity horn with a 1.4 (35.5mm) throat diameter (H64) or a fully rotatable 90 degree by 40 degree 1.4 throat diameter horn (H94). The 60x40 horn or 90x40 will mate directly with the IT 77N or the IT 77F. Use of the IT 44 requires a 35mm to 25mm coupling adaptor that is also available through HC Design. The 152B should be constructed using high quality void free plywood. The use of plywood will allow excellent acoustic performance and minimize enclosure weight. Internal bracing is required to limit mechanical resonances. Acoustic performance above 120Hz is identical for the 152B and 152S. Coverage Pattern: Passive Crossover Frequency: System Sensitivity: (1 watt -1 meter) Power Handling: 50Hz 16kHz 60H x 40V Fully Rotatable (H64) or 90H x 40V Fully Rotatable (H94) 1800 Hz 96dB * NOTE: all system power handling rating are amplifier headroom dependent
Nominal Impedance: System Components: Low Frequency: High Frequency: Dimensions (H x W x D): IT 15 IT 77N/IT 77F/IT 44 778 x 445 x 636.5 mm 152S The 152S is a medium format 15 inch two way enclosure design that is ideal for portable applications. It features less extreme low frequency output then the 152B but offers improved portability. The 152S is a wide bandwidth system design that features very high peak and continuous power handling and extremely high system reliability. The high frequency horn is full rotatable and will all the high frequency radiation pattern to be configured to acoustic spaces. Acoustic performance above 120Hz is identical for the 152B and 152S. The 152S enclosure can incorporate either the H64 or H94 constant directivity horn. (See wiring polarity and configuration notes above for driver and horn selection) The 152S should be constructed using high quality void free plywood. The use of plywood will allow excellent acoustic performance and minimize enclosure weight. Internal bracing is required to limit mechanical resonances. Coverage Pattern: Passive Crossover Frequency: System Sensitivity: (1 watt -1 meter) Power Handling: Nominal Impedance: System Components: Low Frequency: High Frequency: Dimensions (H x W x D): 66Hz 16kHz 60H x 40V Fully Rotatable (H64) or 90H x 40V Fully Rotatable (H94) 1800 Hz 96dB * NOTE: all system power handling rating are amplifier headroom dependent IT 15 IT 77N/IT 77F/IT 44 778 x 440 x 353.5 mm
122S The 122S is a medium format 12 inch two way enclosure design that is ideal for portable applications. The 122S is a wide bandwidth system design that features very high peak and continuous power handling and extremely high system reliability. The high frequency horn is full rotatable and will all the high frequency radiation pattern to be configured to acoustic spaces. The 122S design will accommodate either the H64 or H94 high frequency constant directivity horn. The 122S should be constructed using high quality void free plywood. The use of plywood will allow excellent acoustic performance and minimize enclosure weight. Internal bracing is required to limit mechanical resonances. Coverage Pattern: Passive Crossover Frequency: System Sensitivity: (1 watt -1 meter) Power Handling: Nominal Impedance: System Components: Low Frequency: High Frequency: Dimensions (H x W x D): 65Hz 16kHz 60H x 40V Fully Rotatable (H64) or 90H x 40V Fully Rotatable (H94) 1800 Hz 96dB * NOTE: all system power handling rating are amplifier headroom dependent IT 12 IT 77N/IT 77F/IT 44 698.5 x 368 x 353 mm 122M The 122M is a very high output controlled coverage floor monitor designed for use on both small and large stages. The 112M features excellent vocal range intelligibility and clarity and has been designed to provide superior vocal reproduction even in high ambient noise (loud) environments. The 112M features a controlled low frequency roll off that provides excellent vocal character and a very tight low end response.
The 122M is designed and optimized for high level floor monitor applications. The design incorporates the H94 high frequency constant directivity horn. The H94 may be rotated to optimize monitor and stage coverage. The 122M should be constructed using high quality void free plywood. The use of plywood will allow excellent acoustic performance and minimize enclosure weight. Internal bracing is required to limit mechanical resonances. Coverage Pattern: Passive Crossover Frequency: System Sensitivity: (1 watt -1 meter) Power Handling: Nominal Impedance: System Components: Low Frequency: High Frequency: Dimensions (H x W x D): 70Hz 16kHz 90H x 40V Fully Rotatable (H94) 1800 Hz 96dB * NOTE: all system power handling rating are amplifier headroom dependent IT 12 IT 77N/IT 77F/IT 44 343 x 698.5 x 398 mm 118S/218S The HC Design 118S and 218S are extended low frequency sub woofer designs intended for use with any of the HC Design 15 inch or 12 inch two way loudspeaker systems. The 118S and 218S are professional designs and do not have an associated passive crossover. In professional applications the subwoofer should be set up in a bi-amp configuration. Suggested active filter settings are as follows: 4 th order Butterworth (24dB/Oct) High Pass at 37Hz and 4 th order Linkwitz-Riley (24dB/Oct) Low Pass at 80Hz. A 4 th order Linkwitz-Riley (24dB/Oct) High Pass set to 80Hz should then be used to drive the top box in the system. The 118S features a single IT 18 extended low frequency sub woofer transducer and the 218S features two IT 18 devices for ultra high acoustic power and extended low frequency response. A block diagram of the suggested configuration is shown below. Any high quality Digital Signal Processor (DSP) or analog based crossover (with 4 th order filters) will work well as the crossover
Figure 3: Subwoofer set up with active crossover and Top Box 37Hz 120Hz Recommended Active Crossover Frequency: 80Hz System Sensitivity: (1 watt -1 meter) 96dB Power Handling: 118S 218S 1600 watts Continuous 3200 watts Program 6400 watts Peak* * NOTE: all system power handling rating are amplifier headroom dependent Nominal Impedance: 118S 218S 4 Ohms System Components:118S IT 18 218S 2 ea. IT 18 Dimensions (H x W x D): 118S 785 x 526 x 526 mm 218S
ENCLOSURE DESIGNS All IT Series enclosures should be constructed with 18mm thick void free plywood. Other materials, such as oriented strand board or high density particle board may be used but the highest strength and stiffness to weigh ratio will be achieved with the use of 18mm void free plywood. The enclosures should be assembled using high quality water proof wood glue. The enclosure pieces should be both glued and nailed to insure good joint bonding. The vents for the 118S may be either plastic tubing or cardboard. The outside diameter of the vent material is not critical as long as the wall thickness is the same or greater then specified. HC Design offers a suitable thick wall tube that is highly damped and excellent for sub woofer applications. The internal absorption is an important addition to any loudspeaker enclosure. This material must have the proper acoustic absorption characteristics in order to properly damp the internal vibrations. HC Designs offers acoustic absorption material and strongly suggests that no substitutes be used. The material offered by HC Design is an excellent material and is well suited for use in professional loudspeaker applications. Each IT Series enclosure is shown with internal bracing. This bracing is critical to proper time domain performance and should be both glued and nailed in place. Exact placement of the bracing is not critical.